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M1 <br /> 1 <br /> IN <br /> engineering p c <br /> has adequate capacity to convey the 100-year event. <br /> On-Site Stormwater Management <br /> This project triggers only Minimum Requirements#1 through#5;therefore, according to Chapter <br /> I-2.5.5 of the 2014 SWMMWW,the project shall either use On-site Stormwater Management <br /> BMPs from List#1 for all surfaces, or demonstrate compliance with the LID Performance <br /> Standard. List#1 has been used to assess On-site Stormwater Management BMPs for this project. <br /> Due to existing site and soil conditions in the vicinity of the proposed portable an On-Site <br /> Stormwater Management BMP from List#1 was not feasible. <br /> The following is a list of BMPs reviewed for feasibility for each surface type: <br /> 1. Lawn and landscaped areas: <br /> • Post-Construction Soil Quality and Depth (BMP T5.13): Post-Construction Soil <br /> Quality and Depth will be applied to existing lawn areas requiring replacement due to <br /> being disturbed by construction of the portables, associated walkways, stormwater <br /> pipes,and structures and trenches. <br /> 2. Roofs: <br /> • Full Dispersion(BMP T5.30): A minimum forested or native vegetation flow path <br /> length of 100 feet(25 feet for sheet flow from a nonnative pervious surface)cannot be <br /> achieved. <br /> • Downspout Full Infiltration Systems (BMP T5.10A): Based on geotechnical <br /> evaluation, infiltration is not recommended for this site. Downspout infiltration <br /> systems would not be recommended. <br /> • Rain Garden (BMP T5.14A) or Bioretention (BMP T7.30): Based on geotechnical <br /> evaluation, infiltration is not recommended for this site. Rain Gardens or Bioretention <br /> would not be recommended. <br /> • Downspout Dispersion Systems (BMP T5.10B): Downspout dispersion is not <br /> feasible due to limited site and vegetative flow path downstream of the target surfaces. <br /> • Perforated Stub-out Connections (BMP T5.10C): Based on geotechnical evaluation, <br /> infiltration is not recommended for this site. Perforated stub-out connections would not <br /> be recommended. <br /> 3. Other Hard Surfaces: <br /> • Full Dispersion (BMP T5.30): A minimum forested or native vegetation flow path <br /> length of 100 feet(25 feet for sheet flow from a nonnative pervious surface)cannot be <br /> achieved. <br /> • Permeable Pavement(BMP T5.15):Based on geotechnical evaluation, infiltration is <br /> not recommended for this site. Permeable Pavement is not recommended. <br /> • Rain Garden (BMP T5.14A) or Bioretention (BMP T7.30):Based on geotechnical <br /> evaluation, infiltration is not recommended for this site. Rain Gardens or Bioretention <br /> would not be recommended. <br /> • Sheet Flow Dispersion (BMP T5.12): Sheet flow dispersion is not feasible due to <br /> limited site and vegetative flow path downstream of the target surfaces. <br /> LPD Engineering, PLLC Page 7 Horizon Elementary School — Classroom Portable Installation <br /> Storm Drainage Report,June 5, 2019 <br />